Load platform safety mechanism actuated by load



Nov. 16, 1965 M. DARIMONT 3,217,836

LOAD PLATFORM SAFETY MECHANISM AGTUATED BY LOAD Filed May 17, 1962 INVENTOR lyzarzke fiarzzvzwz Mag 624M ATTORNEYS United States Patent 3,217,836 LOAD PLATFORM SAFETY MECHANISM ACTUATED BY LOAD Maurice Darimont, Rue Secheval 31, Jalhay- Verviers, Belgium Filed May 17, 1962, Ser. No. 195,475 Claims priority, application Belgium, May 29, 1961, 604,352 1 Claim. (Cl. 187-9) The present invention relates to a two-wheel small truck in the form of a hand truck specially designed to lift a weight placed on a platform fixed at the end of a mobile element, sliding on the rails of a metallic structure through the action of a pulling power operated at the other end, and consisting of a first element with a foot lever which runs along the rails of a second element also fitted with a foot lever which in turn slides along the rails welded to the metallic structure.

When acting on each foot lever in turn the platform is brought to the lower end of the rails, which at this spot are provided with casings into which ball bearings are to be lodged. As soon as the load is removed from the platform the operator may disengage the ball bearings from their housings by means of the foot levers so as to bring the platform to the ground level to receive a new load.

The present improvement eliminates the above mentioned action, thus bringing back the platform to ground level automatically as soon as the load is removed from it at the desired height. The platform thus may move down to ground level as soon as the load is removed.

According to one of the characteristics, the platform consists of a rigid frame sliding along rails bearing on arms hanging freely, placed at the inner sides, and supporting a tray for the load.

This load, through the action of springs, displaces a plunger and brings same into a position to permit one of its ends to contact successively two stops welded to the metallic structure at levels respectively slightly lower than the two levels attained by the platform, by the action of the two foot levers, so as to prevent the platform from falling down until the load is removed and the springs force back the plunger into its housing. The ball bearing housings thus become inoperative.

According to another characteristic feature of the invention, a liner is fixed to part of the frame having a passage for the plunger. Said liner contains the above said plunger, circled by two helicoidal springs, one of which acts on one side against the bottom of the liner, whereas the other spring acts against a lobe on the plunger.

At the other end, both springs act against a washer fixed by the fiat head of the plunger, housed in the respective barrel.

As a particularity, the barrel containing the plungers flat head contacts said part of the frame, whereas the other end of the plunger can enter into contact with the stops which can be formed, for instance, by bars inclined for the purpose.

Other characteristics may appear in the following description and the attached drawings, which simply illustrate one way to materialise the invention.

In the drawings:

FIG. 1 is an end elevation showing part of the projection of the platform.

FIG. 2 is a side elevation partly in section, taken on line II-II of FIG. 1 in the direction of the arrows; and

FIG. 3 is a section of a detail.

On these drawings only the main elements necessary to an understanding are included.

As in the known type of this truck, the machine to lift a load is mainly composed of a structure on wheels sliding 3,217,336 Patented Nov. 16, 1965 on the rails of two elements each equipped with a foot lever to be acted upon so as to pull a cable attached to the platform which also slides on rails.

According to the present invention, the platform comprises a frame 1 the sides 1a of which are equipped with rollers 1b rolling on rails 2. Within these sides 1a are fitted two arms 3, swinging on pivots 3a, fixed on a bar 3b, and ending in a platform 30 on which the load is to be placed.

At the lower part of frame 1 there is a horizontal element 4, in the middle of which is provided a hole 4a. Said hole is fitted with a liner 5, having a plunger 6 therein encircled by two springs 7 and 8.

Springs 7 acts at one end on element 4 (bottom of liner) and at the other end on washer 9 whose outward movement is limited by by the fiat head 6a of plunger 6.

The other spring 8 is fixed between the shoulder 6b of the plunger and washer 9, the latter aflixed to a barrel 10 which comes into contact with element 3b.

When a load is placed on platform 30 the barrel 10 pushes washer 9, as shown by arrow X. Said washer acts on springs 7 and 8, the latter pushing in the same direction the plunger 6, the end 60 of which surpasses the face of element 4. By acting on the foot levers and sliding elements (not shown), frame 1 and arm 3 are lifted as shown by arrow Y.

Thus the end of the plunger 60 slides along the slope 11a, then over stop 11 on which it rests, and thus prevents the platform 30 from falling down.

As soon as the load is removed from platform 30, the spring 7 being free, pushes back the washer 9, against arrow X. Said washer 9 acts through flat head 60, on plunger 6, the end 60 of which withdraws into element 4. The platform, no longer supported, drops down automatically to ground level, thus returning to the initial position, ready for a new load.

Therefore the ball bearing housings previously required become unnecessary.

The stops 11 are placed at levels respectively slightly lower than the two respective levels attained by the platform through the action of foot levers (not shown).

I claim:

A load platform safety mechanism actuated by a load for a hand truck comprising a pair of spaced rails, a pair of frame members slidably mounted on the rails, the pair of arms each pivotally mounted at its upper end on a frame member, a platform having a bar member secured to the lower ends of the arms, a member secured to the lower part of the frame members and having a hole therein, a plunger operative with the platform and projecting into the hole, a spring biasing the plunger into engagement with the bar member to pivot the platform to a first position, the placing of a load on the platform pivoting the platform to a second position to project the plunger out of its hole, and a stop having a cam surface mounted on the rails in the path of movement of the projected plunger so that the latter will slide on the cam surface and over the stop to prevent the platform from falling with the load thereon.

' References Cited by the Examiner UNITED STATES PATENTS 1,751,644 3/1930 McKenzie 187-73 X 2,482,211 9/1949 Reichardt 187-9 2,639,150 5/1953 Aberle l8773 X 2,856,028 10/1958 Racely 18776 SAMUEL F. COLEMAN, Primary Examiner.

ANDRES H. NIELSEN, ERNEST R. FALLER,

Examiners. 

